So you are seriously suggesting that each and every GTK+ application
on Win32 comes with an installer that includes it's own copy of GTK+?

Yes I am. Consider it from a user's point of view: I hear about the new
application which might help me, so I go to the website and download the
installer. When I click on the installer, it tells me I need to go off
to another site and download something called a gtk+ runtime. At this
point, there's a decent chance that I'll lose interest and go find
something else to do.